1. Field of the Invention
The present invention relates generally to gear drives and more specifically to an anti-back drive system, which is less complicated than that of the prior art.
2. Discussion of the Prior Art
There are at least three different types of anti-back drive systems, which prevent a drive system from reversing rotation of a gear, after the drive device ceases rotation. Anti-back drive systems are commonly used to slide windows in motor vehicles up and down. A ratchet mechanism may be used to prevent back drive of a gear as shown in U.S. Pat. No. 4,480,733. U.S. Pat. No. 4,480,733 to Grimm et al. discloses an energy absorbing bi-directional ratchet no-back apparatus. The Grimm et al. patent discloses an energy absorbing ratchet for a bi-directional no-back apparatus which includes in combination a fixed support, a rotatable input member and a rotatable output member.
A worm gear is commonly used to prevent back drive of a gear as shown in U.S. Pat. No. 7,140,151. U.S. Pat. No. 7,140,151 to Spaziani et al. discloses an electro-mechanical actuator. The Spaziani et al. patent includes a window lift mechanism including a plurality of motors for driving an output shaft. A clutch spring mechanism is also commonly used to prevent back drive. Patent application no. 2009/0315380 to Nae discloses an anti-back drive device for releasably securing a seat back with respect to a seat cushion. The Nae patent application includes an upper gear plate affixed to the seat back and defines gear teeth. A lower gear plate is secured to a seat bottom and defines gear teeth that cooperate with the upper plate gear teeth.
Accordingly, there is a clearly felt need in the art for an anti-back drive system, which includes a less complicated construction than that of the prior art.